The effect of aging on superelasticity of TiNi SMA was studied by mechanical property tests. It’s indicated that after aging treatment of 300℃×(60-180min) and aging treatment of 400℃×(10-30min), the tensile strength of TiNi SMA wires is higher than 1000 MPa, and the residual strain is less than 0.31% in loading-unloading tensile tests of 6%. The low clearance TiNi SMA has better mechanical properties and superelasticity after aging treatment.